Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
ManageEngine OpUtils - ManageEngine OpUtils is an IP address and Switch port management software that includes a comprehensive set of 30+ tools that helps network engineers monitor, diagnose and troubleshoot their IT resources.
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
BlueCat DDI - Unify your DDI (DNS, DHCP and IPAM) solutions to make DDI data an engine for innovation and growth.
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.
phpIPAM - phpipam is an open-source web IP address management application (IPAM).